Moved this from Open Freshwater...

Well I decided to take care of some repairs on the boat since the high water closed most of the ramps on my local lakes. I had one of my two bilge pumps go out so I cut the wires and put a new one in but no juice.

I figured the wire corroded so I removed the deck (2001 Logic 17' cc) and untangled the wires and cut away
a thousand feet of ten year old electrical tape all the way to the panel on the center console. No joy so I removed the panel and tested the switches, no problem but no power. I sat there staring at the panel for an entire beer when I noticed the switch had a button beneath it that I had never really looked at before. I pressed the button and it clicked and the bilge pump started working. Apparently it was a micro circuit breaker that had popped because of the bad pump.

Well, great! I put the panel back on and retaped the wiring and put the deck back on (on a Logic it is one pure PITA) and remounted the seat on the deck and reattached the battery cables and the bilge pumps both worked but the horn wouldn't.

So the next day I get home from work and try the radio and the depth finder neither work. I check the battery again and realize I hooked the negative to the positive and vice versa. I change them back and now the horn and bilges work but the radio and depth finder are dead.

Sooooooo. Does reversing the power cables destroy depth finders and radios? If I have to take the deck off again I might just grab my Uzi and head to McDonald's. (Just kidding, ATF)

Check for blow fuses going to depth finders and radios first.

Yes, both inline fuses are good.

I know that it is possible to fry ecu in a car if you put cables on wrong, or jump it incorrectly (cables switched) make sure all your connections are secure and cables put in proper place. pull out the old multimeter and start checking power to each device to see if they are getting power. i hope this helps.